Thermostatic material



' 45 oxidation.

'' mama Nov. 29,1 21.

roimm a. men, or wnlxnisnune,

morale rmmsrnvmul, a murnc'ruamo cournmr, A oonronarron or rnnmlos'ra'rrc MATERIAL;

Application am March '12,

erature con- My invention relates'to tem y to thermotrolled devices and particular static material.

The objgctof my invention is to provide a metallic thermostat that shall operate properly over a relatively large temperature range, that. hall resist oxidation at h1gh temperatures, and that shall retain its operating characteristics even after a long con- 10 tinued use. 0

In practicing my invention, I provide a thermostat com rising metallic elements one of. which ismo ybdenum and the other of which is an alloy of chromium and cobalt l and which may also contain iron. An 0x1- dation-resistant coating of electrolytic chr0- mium is also provided over the outer entire surface of the thermostatic member.

In the-single figure of the accompanymfi drawing, I have illustrated, in long1tu 1 n section, the device embodying my invent on. The use of two metals, intimately umted over their entire adjacent and abutting surfaces, for obtaining a movement of one part thereof relatively to the other part under I temperature changes is well known, partlcularly for relatively low temperatures. When the problem is presented of roviding such a metallic thermostat for re atively high temperatures and. for relatively large temperature changes, it is one that is not easily solved, particularly by. the use of the metals heretofore employed, as these metals lose their original characteristics and also 36 oxidize at the relatively high tem eratures. These temperatures may be as big as 600 "C. oreve'n up to 800 C. I have found that molybdenum has a relatively high elastic limit, even-when heated to the hereinbefore 40 mentioned high temperatures, and I have also found that certain alloys of chromium and cobalthave relatively high strength at the high temperatures hereinbefore together with a relatively great resistance to j Molybdenum has a mean or average temperature expansivity of approximately 6X 10" between the limits of 0 'while an alloyof chromium and. cobalt containing ap roximately of cobalt (1 approximate y 20% of chromium has a mea r v average temperature expansivity of'approximately 17x10" between 0 C. and800 and is a ductile alloy.

I have foundthat an alloy containing mentioned,

G. and 800 (1.,

approximately mium and 56% Molybdenum oxidizes open'alr to temperatures above-500 G. and

r oerce.

Assmuon ro wns rnrcnousn mmI-vmm 1925. Serial 10. 1M

of iron has a tem .erature expansivity and] emp oyed as one of the metallic elements in a metallic thermostat.

cobalt, 22% of cm slightly higher could also be a o when heated in the must, therefore, be protected against such oxidizing action w ploy the device at tem eratures above limit.

In the drawing,

hen-sit is desired to emv A- deposit of electrolytic chromium or of" a chromium-nickel alloy over thermostatic element will accom the finished lish this.

esignates a suitably numera 11 70 as been united with a substantially similar strip 12 ofa chromium-cobalt alloy in a manner well known in the art to bimetallic thermostat. dicates a coating of mium-nickel alloy constitute the so-call The numeral13 in- 75. chromium or of a chrothat has .been electroplated thereon over substantially the entire surface to provide coverlng or coating.-

an oxidation-resistant I have found that a number of alloys of cobalt and chromium, having difierent proportions. of the two metals therein, may be employed, and I have centage of cobalt may range from 70% centage of chromium varying to approximate y mately 30% I do not specifica admixtures of othel'f usually present 1n in a cobalt chromium all oy found that the to with'the perfrom ap roxi-' 10%. -1e ly claim relatively small. metals, such metals are very small quantities and may include manganese, silicon, tungsten,

carbon, etc.

impurities,

These tities of other metals that are important from relatively small quanmay be termed a metallurgical standpoint, as they ensure sound and forgeable ingots.

I have hereinbeforementioned the possibility of the use of and such all of cobalt, 30% to 10% the balance being1 alloy, 10% to 30% mium, small quantities of a cobalt-chromium-iron oys may contain m of chromostlyiron, and er materials, menthe tioned above in connection with the cobalt chromium alloys, forgeable ingots.

as ensurmg sound and A device embod these metals when G. properly rolled an tion properly over perature range of heat treated, will functherelativel large temeubstanti y o? G. to no this,

I plurality 800 C; will retain itsoperating characteris tics even when subjected to long continued use under the relatively large temperature variations and the relatively high maximum temperatures and will be substantially oxidation-resistant because of the electro-deposited coatingof oxidation resistant metal or alloythereon.

Since various modifications and changes may be made Without departing from the spirit-and scope of the invention. I desire that only such limitations shall be placed thereon as are imposed by' the prior art.

I claim as my invention:

1. A heat-responsive device comprising a plurality of'metallic elements, one of said elements being a ductile chromium-cobalt al- 10y and the other element being molybdenum.

2. A heat-responsive device comprising a plurality 'of metallic elements, one ofsaid elements being a ductile chromium-cobalt alloy, the other element being molybdenum, and an oxidation-resistant coating of chromium on both said elements.

3. 'A heat responsive device comprising a plurality of metallic elements, one of said elements being a ductile chromium-cobalt alloy having an appreciable admixture ofiron, and the other element being molybdenum.

4. A heat responsive device comprising a elements being a ductile chromium-cobaltof metallic elements, one of said alloy havin an appreciable admixture of iron, the ot or element. being molybdenum, and an oxidation resistant coating of electrolytic chromium. I

5. A heat-responsive device comprising a plurality of metallic elements, one of said elements being a ductile chromium-cobalt plurality of metallic elements, one of said elements being molybdenum and the other element being a ductile oxidation resistant alloy containing chromium, the latterelement cobalt and having a mean temperature expansi'vity greater than 16X10' for a temperature range of from 0 C. to substantially In testimony whereof, I have hereunto subscribed my name this 9th day of March,

PORTER H. BRACE.

of cobalt, substantially all of 

